Bald Eagle

North America has only one native sea eagle, and it wears the continent's most recognized profile: a white head and tail set against a solid dark brown body and a hooked yellow bill. That bird is the bald eagle, Haliaeetus leucocephalus.

A member of the family Accipitridae within the order Accipitriformes, the bald eagle ranges across most of Canada and Alaska, the entire contiguous United States, and northern Mexico. It comprises two recognized subspecies and is currently assessed as Least Concern by the IUCN, a status that reflects one of the most dramatic conservation turnarounds of any North American bird.

Beyond its symbolism, the species has a compelling backstory: a bird that nearly vanished from most of the lower 48 states by the mid-20th century and has since rebounded so strongly that it now nests in every province and state across its range.

The clearest field mark is the contrast between a solid dark brown body and a pure white head and tail, set off by a large, hooked yellow bill, yellow eyes, and bare yellow legs. Within its native range, no other raptor combines these features, making an adult bald eagle unmistakable.

Adults measure 70 to 102 cm (28-40 in) in body length, with a wingspan typically between 1.8 and 2.3 m (5 ft 11 in-7 ft 7 in) and a body mass usually between 3 and 6.3 kg (6.6-13.9 lb). Females run about 25% larger than males, averaging near 5.6 kg (12 lb) against a male average of roughly 4.1 kg (9 lb), though the sexes are identical in plumage color.

Juveniles look entirely different: a mottled patchwork of dark brown and messy white streaking that persists until the bird reaches sexual maturity around its fourth or fifth year. Immature bald eagles are sometimes confused with the golden eagle, but the bald eagle's larger, more protruding head, bigger beak, flatter wing profile held straighter in flight, and bare lower legs set it apart from the golden eagle's smoother, warmer brown plumage and feathered legs.

Size also tracks latitude, following Bergmann's rule: eagles grow larger the farther they live from the equator. Birds from South Carolina average only 3.27 kg (7.2 lb) with a 1.88 m (6 ft 2 in) wingspan, while the largest individuals, from Alaska, can weigh more than 7 kg (15 lb) and span 2.44 m (8 ft) across the wings.

The bald eagle's range covers most of Canada and Alaska, the entire contiguous United States, and northern Mexico, making it the only sea eagle native to the continent. It favors seacoasts, rivers, large lakes, and marshes with abundant fish, showing a strong preference for water bodies with a shoreline longer than 11 km (7 mi) and a surface area greater than 10 km² (4 sq mi).

Nesting depends on access to old-growth or mature forest close to that water. Nest trees are usually over 20 m (66 ft) tall, stand in stands with 20 to 60 percent canopy cover, and sit within about 200 m (660 ft) of open water, though birds in Florida have nested more than 3 km (1.9 mi) from shore. Where trees are unavailable, such as on Alaska's Amchitka Island or in the deserts of Sonora, Mexico, eagles instead nest on cliffs, the ground, or even cactus.

Regional populations behave differently: northern breeders migrate, while many southern populations, including much of Florida's, stay on territory year-round. Large winter concentrations gather where fish remain accessible, such as one to two thousand birds along British Columbia's Squamish and Cheakamus Rivers between November and February, drawn by spawning salmon. The species also turns up as a rare vagrant, with confirmed records from Ireland in 1973 and 1987.

Monthly observation counts, which record presence rather than abundance, climb from roughly 850,000 in January to a peak near 888,000 in May, drop sharply through June, July, and August to under 410,000, then rise again through the fall. That pattern likely tracks breeding-season activity and visibility near nests rather than a true change in population size.

Migration strategy varies by population rather than following one fixed pattern. Yellowstone eagles migrate only short distances for better foraging, southern populations such as many in Florida stay resident, and Canadian breeders move into the United States for winter, often following the Mississippi River as a migratory corridor. Great Lakes birds may shift toward the Chesapeake Bay, while eagles from the northeastern United States and Canada often move south into the Appalachian Mountains.

In flight, the bald eagle glides and flaps at 56 to 70 km/h (35-43 mph), slows to around 48 km/h (30 mph) when carrying fish, and can dive at 120 to 160 km/h (75-99 mph), though steep vertical dives are rare. Hunting typically means swooping low over water to snatch fish near the surface with its talons, aided by spiny structures on the toes called spicules; the bird does not submerge itself. It also strikes birds up to the size of Canada geese in midair, and pairs sometimes hunt cooperatively, with one eagle distracting large prey like jackrabbits or herons while the other ambushes from behind.

Despite these hunting skills, bald eagles get much of their food as carrion or by kleptoparasitism, stealing catches from ospreys and other eagles. A detailed time budget found the birds resting about 91 percent of the time, with only small fractions spent drinking, scavenging, or pirating food, and activity drops further in winter, high wind, or rain.

Bald eagles are largely solitary outside the breeding season but will roost communally in groups of up to 400 birds where food is concentrated. Pairs become territorial once nesting begins, defending home ranges that average 1 to 2 km², though Oregon pairs have held territories as large as 47 km² and Alaskan birds have persisted on ranges as small as 0.5 km², believed to be the species' lower limit.

Contrary to its fierce reputation, the bald eagle's voice is thin and high-pitched rather than powerful. It produces three main calls: a chattering series described as kwit, kwit, kwit, kee-kee-kee-kee-ker, a wail, and a peal, a long, high cry given when the bird perceives a threat.

Visual signals matter as much as sound. Eagles communicate threat and intent through head motions, wing motions, and crouching postures, and breeding pairs greet each other at the nest with calls paired with dramatic flight displays.

Large, forward-facing eyes give the species strong binocular vision, its primary sense for hunting and signaling. Smell is weak by comparison, though the birds can still detect and avoid food that has begun to spoil.

The bald eagle hunts mainly by sight, perching to scan open water before swooping down and snatching fish near the surface with its talons rather than diving underwater. Spiny structures on its toes called spicules help it grip slippery prey, and its grip strength has been estimated at ten times that of a human hand. It can carry fish roughly equal to its own body weight, but if a catch is too heavy to lift, the eagle may be dragged into the water and risk drowning or hypothermia.

Fish make up the bulk of its diet, including rainbow trout, chum and kokanee salmon, American eels, gizzard shad, white catfish, rock greenlings, Pacific cod, Atka mackerel, and largemouth bass, among others. It also takes adult water birds, nestlings, and eggs, preying on species such as common murres, great blue herons, snow and Ross's geese, tundra swans, northern fulmars, auklets, American coots, and common loons, occasionally striking large birds like geese in midair.

Diet shifts with the seasons: in winter, bald eagles turn more heavily to carrion and small mammals, hunting ground squirrels, montane voles, Norway rats, and even sea otter pups, while scavenging the carcasses of elk, moose, mule deer, caribou, bison, wolves, and arctic foxes. Populations near landfills also feed on human refuse.

Beyond direct hunting, the species relies heavily on kleptoparasitism, stealing food from ospreys and other raptors, especially among younger, smaller birds that hunt less often than adults. Human disturbance near foraging grounds can cut feeding activity by as much as 35 percent, but the eagle can fast for several days and stores up to 1 kg (2.2 lb) of food in a throat pouch called a crop to get through lean periods.

Bald eagles are monogamous and typically mate for life, choosing a new partner only if one dies or disappears, or after repeated breeding failures. Pairs reunite each season with elaborate courtship flights, including a cartwheel display in which both birds lock talons in midair and spiral toward the ground, releasing just before impact. Breeding begins around four to five years of age.

Both sexes build or reinforce the nest, usually one to three months before laying, in the tallest available trees near water, though pairs in southern Florida use mangroves and some populations nest on cliffs, the ground, or even utility structures. Nests are reused and expanded year after year: the largest on record, in Florida, reached 2.9 m (9.5 ft) wide and 6.1 m (20 ft) deep and weighed roughly 3 short tons before it fell. Nest lifespan varies by region, averaging about 5 years in southern Florida and Saskatchewan but 13 years in Alaska, with one Midwest nest used continuously for 34 years.

Clutches contain one to three eggs, most often two, laid at times that shift with latitude: as early as October in Florida and as late as March in Yellowstone. The whitish, oval eggs average about 73 mm (2.9 in) long and tend to be larger at higher latitudes. Incubation lasts about 35 days regardless of location, shared by both parents, though the female does most of the sitting.

Chicks hatch semi-altricial at around 60 g (2 oz) and can gain up to 180 g (6.3 oz) a day on food delivered by both parents four to five times daily. They fledge between 8 and 14 weeks of age but may stay dependent on their parents for up to 18 weeks. When food or space is limited, the oldest, loudest chick sometimes attacks and kills younger nest mates, though close to half of all nests still successfully raise two fledglings.

As an apex predator across its wetland and coastal habitats, the bald eagle shapes the populations of the fish and birds it hunts and scavenges. Its 20th-century decline and later recovery had ripple effects through its food web; the rebuilding eagle population, for instance, has been linked to renewed pressure on common murre colonies.

The species also carries a range of parasites and pathogens, including the protozoan Toxoplasma gondii, along with trematodes, an acanthocephalan, and several genera of nematodes, evidence of its position within a broader web of predator-prey and host-parasite relationships.

The bald eagle is currently listed as Least Concern by the IUCN, reflecting a large range and a population that has grown substantially since its low point in the mid-20th century. It was removed from protection under the U.S. Endangered Species Act on June 28, 2007, after decades on the list.

The decline that made that listing necessary was severe: hunting, habitat loss, and especially the pesticide DDT drove the species from an estimated 300,000 to 500,000 individuals in the early 18th century down to just 412 nesting pairs in the contiguous United States by the 1950s. DDT accumulated in the eagles' fat through biomagnification, disrupting calcium metabolism so severely that eggshells became too thin to survive incubation.

Legal protection began with the 1918 Migratory Bird Treaty and strengthened with the Bald and Golden Eagle Protection Act of 1940, which banned commercial killing and egg collection. The species was declared endangered in the U.S. in 1967, and the 1972 U.S. ban on DDT, followed by Canada's in 1989, allowed the population to rebound. By 1998 there were 5,748 nesting pairs in the contiguous states, Alaska held between 20,000 and 25,000 birds by 1993, and Washington State's population grew roughly 700 percent between 1981 and 2005.

Remaining threats include lead poisoning, which a 2022 study in the journal Science found affects more than half of adult eagles across 38 U.S. states, mostly from scavenging carcasses tainted with lead shot, rifle rounds, or fishing tackle. Collisions with vehicles, power line electrocution, mercury contamination, coal plant emissions, and climate change add further pressure.

The bald eagle has been the national symbol of the United States since 1782, appearing on seals, coinage, postage stamps, and government emblems; it also features on the coat of arms of the Philippines, marking its former status as a U.S. territory even though the bird is not native there.

Its significance runs deeper in Native American traditions, predating the United States by thousands of years. Bald eagle bones found at the Frisby Butler site may connect to Thunderbird ceremonialism, and eagle feathers remain central to spiritual practice among peoples including the Lakota, who present a feather as an honor for achievement, the Navajo, who use eagle bones for ceremonial whistles, the Pawnee, who see the eagle as a symbol of fertility, and the Choctaw, who regard it as a symbol of peace. In the Sun Dance ceremony practiced by many Plains tribes, an eagle-bone whistle and an eagle-feather fan are used to carry prayers for healing toward the Creator. U.S. eagle feather law restricts possession of bald and golden eagle feathers to enrolled members of federally recognized tribes, and the National Eagle Repository collects and distributes eagle remains for that religious use.

In modern popular culture, the bird stands for freedom, democracy, and environmental ethics, and its charisma drives substantial ecotourism; birdwatching in the United States has been estimated to involve 20 to 30 million people generating around 20 billion dollars annually. Ironically, its real call is often considered too weak for film and television, which frequently substitute the louder cry of the red-tailed hawk.

1. Despite the eagle's fierce image, its real voice is a thin, chattering call, so weak that film and TV often dub in the louder cry of a red-tailed hawk instead.
2. Its closest living relative is the white-tailed eagle, which fills the same ecological role across Europe and Asia.
3. Archaeological finds link bald eagle bones to possible Thunderbird ceremonialism among ancient indigenous cultures.
4. The bald eagle has been the official U.S. national symbol since 1782, more than two centuries of continuous use.